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Unformatted text preview: hyun (hh7953) – Homework 1 – Sparks – (53435) 1 This print-out should have 29 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. Remember, you are encouraged to work on the problems and enter your answers a few at a time as we cover the topics in class. Don’t wait until right before the due time to work on the problems and submit answers! You could run into server problems and you certainly will not have time to get help and resubmit answers for problems you discover you do not know how to do. Keeping up with the problems as we cover the topics in class will help you understand more in class and result in less study time needed overall. 001 10.0 points Which of these describes a chemical prop- erty? 1. Ne is not combustible. correct 2. NO 2 is an amber-colored substance. 3. Palladium has a high boiling point. 4. Sodium is soft metal. 5. Copper is a solid at room temperture. Explanation: Chemical properties always involve the change of a substance into another. If Ne were to burn, it would be converted into some other compound (some oxide of neon). The other properties described here are all physical properties. None involve a chemical change. 002 10.0 points All of the following are characteristic prop- erties of oxygen. Which one is a chemical property? 1. Oxygen boils at- 183 ◦ C. 2. Elemental oxygen exists as a diatomic gas at room temperature. 3. Oxygen makes up about 20% of our at- mosphere. 4. Oxygen can combine with metals. cor- rect Explanation: Chemical properties are exhibited as mat- ter undergoes a chemical changes. A chemical property of the metal is that it can combine with oxygen, releasing energy in the process. A chemical property of oxygen is that it can combine with the metal. 003 10.0 points Which of the following involves a chemical change? 1. chopping wood 2. breaking a glass 3. boiling water 4. cooking an egg correct Explanation: A chemical change occurs when one or more substances are consumed (at least partially), and one or more new substances are formed. The conversion of some substances into other substances causes the observed prop- erties of the sample to change. The incor- rect answers suggest physical phase changes or breaking down into smaller pieces of the same composition. Cooking an egg results in different properties (color, etc.) which do not change back to the original properties when the egg is cooled. Thus cooking an egg repre- sents a chemical change....
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This note was uploaded on 01/19/2010 for the course CH 53435 taught by Professor Sparks during the Fall '09 term at University of Texas.
- Fall '09